This library implements a data-structure that supports the next workflow (taken from wikipedia)

With this method, there are 12 boxes. One is the Current Deck, one is the Retired Deck, and the remaining 10 boxes are named with these numbers:

• 0-2-5-9
• 1-3-6-0
• 2-4-7-1
• 3-5-8-2
• 4-6-9-3
• 5-7-0-4
• 6-8-1-5
• 7-9-2-6
• 8-0-3-7
• 9-1-4-8

Learning sessions are numbered from 0 to 9, then the numbering starts over again (i.e. 0, 1, 2, ..., 8, 9, 0, 1, 2, ...).

All cards begin in Deck Current. All cards in Deck Current are done at every learning session.

If a learner is successful at a card from Deck Current, it gets transferred to the deck that begins with that session's number. For example, if this is session 0, a successful card in Deck Current moves to box 0-2-5-9; If this is session 3, a successful card from Deck Current moves to box 3-5-8-2.

A box of cards is reviewed when its name contains the current session number. For example, if this is session 0, boxes 0-2-5-9, 1-3-6-0, 5-7-0-4, and 8-0-3-7 are done because they all contain the number 0.

If a reviewed card isn't successful, it moves back to Deck Current.

If a reviewed card is successful and the last number of its box matches the current session number, then that card moves to the Retired Deck. For example, if this is session 9 and you're reviewing box 0-2-5-9, then any successful cards from this box will move to the Retired Deck.

If a reviewed card is successful and the last number of its box doesn't match the current session number, then that card stays where it is.

The effect is identical to a 5-box Leitner system, however, whereas in that system each box represents the proficiency level of its contents, here each box represents the session in which it is done.

Basic flow might look something like this

export {
  addToUnknown,
  createLeitnerBox,
  moveToLearned,
  moveToLessons,
  setCurrentLesson,
  isLastLessonForCard,
  getCardsForCurrentLesson
} from 'leitner-box';

let cards = [
  { word: "learn", translation: "aprender" }
  { word: "box", translation: "caja" }
];

let leitnerBox = createLeitnerBox();

cards.forEach(card => {
  leitnerBox = addToUnknown(leitnerBox, card);
});

// then, after initial acquaintance we move cards from "unknown" to "lessons"
// for subsequent repetitions
cards.forEach(card => {
  const identity = ({ word }) => word === card.word;
  leitnerBox = moveToLessons(leitnerBox, identity);
});

// then, after we done with unknown we might want to move to the repetition
cards = getCardsForCurrentLesson(leitnerBox);

// and at some point switch current lesson
leitnerBox = setCurrentLesson(leitnerBox, (getCurrentLesson(leitnerBox) + 1) % 9);

// at the end we might want to put cards into "learned" box
// make sure to check if this is the last repetition for the card
cards.forEach(card => {
  const identity = ({ word }) => word === card.word;

  if (isLastLessonForCard(leitnerBox, identity)) {
    leitnerBox = moveToLearned(leitnerBox, identity);
  }
});

For more examples please consider looking into specs

To create a new version do the following steps

• Bump version in package.json
• Create a new tag (for example git tag v1.0.10)
• Push tags into origin git push origin --tags